This invention relates to an electrophotographic member, more particularly to an electrophotographic member with long life and high reliability, made from a hydrogenated amorphous silicon-containing material, and capable of forming good images without producing image blurring even if printed under high humidity after printed repeatedly, and a process for producing the same and an electrophotographic apparatus using the same.
As electrophotographic members, there have been used inorganic photoconductive materials such as Se, CdS, As.sub.2 Se.sub.3, etc. and organic photoconductive materials such as phthalocyanine pigments. These materials are excellent in electrophotographic properties such as charge acceptance, photo response, photoconductivity, etc., but are disadvantageous in mechanical properties, e.g., low in hardness and poor in wear resistance. In contrast, since amorphous silicon photoreceptors are high in hardness and excellent in wear resistance, they are expected to be long-life electrophotographic members.
But, the amorphous silicon photoreceptors have a defect in that they are poor in moisture resistance. In order to improve moisture resistance, a surface protective layer made of a--SiC:H, a--SiN:H, etc. is generally provided. But, this is still insufficient.
In a printing process in electrophotography, since there is a charging process by corona discharge, the surface protective layer is oxidized and deteriorated in the moisture resistance by the repetition of printing process. In order to prevent the deterioration of moisture resistance, there are proposed to use as the surface protective layer an a--C:H:F film (Japanese Patent Unexamined Publication No. 63-191152) and thermoplastic resin films (Japanese Patent Unexamined Publication Nos. 55-142352 and 55-70848). But according to these surface protective layers, there is a problem in that both the moisture resistance and other properties required for surface protective layers of electrophotographic members, i.e. wear resistance and cleaning properties, are not always satisfied. Particularly in the case of using fluorine-containing materials as the surface protective layer, the moisture resistance is improved remarkably, but the wear resistance and cleaning properties are remarkably lowered.
On one hand, Japanese Patent Unexamined Publication No. 55-7762 discloses to include a perfluoroalkenyl group-containing compound in at least one layer constituting an electrophotographic member. Japanese Patent Unexamined Publication Nos. 56-51754, 58-23031 and 58-102949 disclose electrophotographic members and electrostatic image acceptors containing a solvent-insoluble polytetrafluoroethylene powder, e.g. a particle size of 20 .mu.m or less, as a fluorine-containing compound in a surface layer.
On the other hand, Japanese Patent Unexamined Publication Nos. 58-23031, 58-102949, 61-205950 and 62-206559 disclose electrophotographic members and electrostatic image acceptors including perfluoroalkyl group-containing surface active agents or silane coupling agents as fluorine-containing compounds in a surface layer. In this case, the perfluoroalkyl group is represented by the formula: C.sub.n F.sub.2n+1 --, wherein n is about 20 at most, limiting the length of fluorine chain. Thus, hydrophobic property may be improved due to exposed fluorine chain on the surface, but effects for reducing the coefficient of friction and improving lubricating properties are not so much, which results in making electrophotographic members poor in wear resistance and cleaning properties even if these fluorine-containing materials are included therein.
Further, in the case of including a polytetrafluoroethlyene powder, since the polytetrafluoroethylene is poor in affinity for other resins and is easily released, there is a problem of being poor in wear resistance.
As mentioned above, prior art techniques are insufficient in satisfying all the properties, that is, moisture resistance, wear resistance and cleaning properties, required for the surface protective layer of electrophotographic member, and have problems in that defects of a--Si:H photoreceptor are not overcome sufficiently, e.g. image blurring occurs after repetition of printing process, particularly under high humidity.